What is one reason why cancer cells can continue to proliferate indefinitely?

Cancer cells are characterized by their ability to proliferate indefinitely, which is largely due to their limitless replication potential. Unlike normal somatic cells, which have a finite number of divisions they can undergo before senescence (the Hayflick limit), cancer cells often bypass this limitation. This is primarily because many cancer cells maintain or activate telomerase, an enzyme that extends the telomeres at the ends of chromosomes. In normal cells, telomeres shorten with each division, leading to eventual cell death or senescence. However, cancer cells can continuously rebuild their telomeres, allowing them to evade the normal cellular aging process and keep dividing indefinitely. This ability is a central hallmark of cancer and differentiates malignant cells from normal cells, leading to tumor development and progression.